The invention relates to a device for imaging layers of a three-dimensional object. The device includes a radiation source arranged to irradiate an object under examination with penetrating radiation from each of a plurality of source positions which are distributed in a common radiation source plane. The device also includes an examination table on which the object is arranged, and a record carrier which is situated underneath the object to record an encoded composite image of the object. The encoded image consists of a plurality of perspective images (corresponding to each source position) which can overlap one another.
A device of the kind described above is known from German Offenlegungsschrift No. 26 05 497. In this device, an object is irradiated from different perspective directions by means of a multiple radiation source which consists of several separate radiation sources which are situated in one plane. A source distribution encoded composite image of the object is recorded on a record carrier which is arranged underneath the object. The composite image can subsequently be decoded in order to form images of layers of the object, for example, by the decoding method described in German Offenlegungsschrift No. 24 14 322.
However, the formation of the encoded images by means of the device of Offenlegungsschrift No. 2605497 has the drawback in that the superposed imaging of central projections from different perspectives causes superposition artefacts in the decoded image. Such artifacts are due to object structures, for example bones, which are not situated in the region of interest in the selected sectional layer of the object. As a consequence the quality of a decoded sectional layer image is reduced.
It is also a drawback that all superposed central projections are imaged with a comparatively large contrast range. As a result, in the film region which is strongly exposed by a central projection, object information which is projected on the same film region from other perspectives is lost. The contrast range of a layer image or zonogram is essentially smaller than that of a central projection.